In the field of materials testing, it has been a general practice to employ automated devices for acquisition of a liquid sample to be tested, transport of that sample to a testing apparatus, retrieval of the tested sample from the testing apparatus, and finally return of the sample whence it came or else provision of the tested sample to appropriate disposal. Often, such devices, particularly owing to their automatic nature, are designed or adapted to engage, transport and release samples of a predetermined size. However, there can be a need to have such specialized material handling apparatus also handle samples or containers of a different (e.g. smaller) size for which it was not designed. For example, this can occur when the testing device, for which the handling apparatus transports samples, is to be used for a different kind of sample than that for which the handling apparatus had been designed, intended or expected to use. For such situations, it is highly desirable to be able to adapt the handling apparatus to also handle such other samples, rather than replace that handling apparatus with another one. Replacement, instead of adaptation, would necessarily involve additional expense for the additional handling apparatus, as well as delay and expense in disassembling or deactivating the existing handling apparatus in order to install or activate the additional handling apparatus. This problem is overcome by the present invention.
One example of a prior art testing device and a prior art material handling apparatus is shown in FIG. 1. FIG. 1 shows a magnet chamber 13 of a nuclear magnetic resonance (NMR) spectrometer. Samples of liquid material are tested by the NMR spectrometer in magnet chamber 13. Such liquid samples are inserted in and removed from chamber 13 via room temperature shim assembly 15. Provision of samples of liquid material to assembly 15 and removal of those liquid samples therefrom is accomplished by material handling apparatus 17. Apparatus 17 includes a vertical cylinder 19 and piston 21 mounted on a rotatable arm 23. The lower end of piston 21 is provided with a pincher 37 for engaging and carrying a liquid sample. Arm 23 is rotatably supported on motorized pole 25 by upper and lower fixture rings 27 and 29 each connected to arm 23, and by resting ring 31 on which lower fixture ring 29 rests. Pole 25 is also provided with a pipe or tube 33 which supports magazine belt 35. Magazine belt 35 is configured to hold a plurality of liquid samples, and is rotated with rotation of pipe 33 so that different samples can be presented at different times to pincher 37. Cabinet 39 provides controls for movement of pipe 33 and pole 25. Pincher 37 with cylinder 19 and piston 21 can be moved horizontally or radially along arm 23, and may be moved azimuthally by swinging of arm 23 by rotation of pole 25 caused by cabinet 39. Pincher 37 is connected to the lower end of piston 21, and can be controlled to open and close about a liquid sample at belt 35 and cylinder 15. Cylinder 19, piston 21, arm 23 and pole 25 can thereby move pincher 37 between belt 35 and assembly 15.
Pincher 37 is shown in greater detail in FIG. 2 in a different stage of operation from that of FIG. 1. Fingers 41 can be furthermore extended further apart beyond the position of FIG. 2 so that liquid container 45 can be inserted therebetween. Pincher 37 includes a plurality (for example, five) of angled claw members or fingers 41 with a rigid collar 43. Fingers 41 are spring loaded to tend to stay together by an O-ring (not shown) disposed under collar 43. Although cylinder 19, piston 21 and fingers 41 are pneumatically activated, nonetheless hydraulic and/or electrical activation or control can alternatively be accomplished. Fingers 41, and especially slidable inner piston 42 to which the fingers are connected, move down and up, or out and in, as the fingers extend or retract, respectively. Fingers 41 can thereby be extended and retracted between their respective positions of FIGS. 1 and 2, or even beyond the latter position.
The lower portion of piston 21 is hollow, and is provided with a pneumatically (or otherwise) actuated and controlled slidable hollow cylindrical inner piston 42 coaxially and slidably disposed within the hollow portion of piston 21. Inner piston 42 has a cylindrical hollow 44 therein. Hollow 44 is open at the end of piston 42 at which fingers 41 are disposed. Fingers 41 are pivotably connected near the lower end of inner piston 42. As inner piston 42 moves downwardly in piston 21, the bends 46 of fingers 41 are moved free of collar 43, permitting the fingers to spread apart. Conversely, as inner piston 42 is withdrawn into or moved upwardly in piston 21, if fingers 41 had already been spread open, then the inner surface of collar 43 engages the bends 46 of those fingers, thereby drawing the fingers together. Since the liquid sample containers are generally made of glass, and so are frangible, it is necessary to control fingers 41 to grasp such containers firmly but gently.
The prior art apparatus of FIGS. 1 and 2 is designed for handling and testing of liquid samples such as are contained in liquid sample container 45 of FIG. 2. However, solid samples are disposed in holders or rotors 51 which are several times smaller than liquid containers 45. In particular, as shown in FIG. 2A, solid samples are disposed in rotor 51. Rotor 51 includes cap 47 and tube 49. Cap 47 is tightly press fitted on tube 49 whose opposite end is closed. Inside chamber 13, the toothed or ratcheted edges of cap 47 are engaged by compressed air to rotate the sample in a technique known in the art as "magic angle" spinning. For this reason, cap 47 and tube 49 are together known as a rotor 51.
A device such as that shown in FIGS. 1 and 2 is for example available from Bruker Instruments, Inc., Billerica, Mass. Alternatively, the samples and their containers or holders can be mounted on a moving carousel or turbine which is not mounted on pole 25.
Since rotor 51 is considerably smaller than the liquid containers 45 which pincher 37 is designed to engage, problems have been encountered in attempting to utilize pincher 37 to grip and carry rotor 51. Also, because of its larger size, container 45 can be raised out of assembly 15 by a cushion of air and supported thereby until engaged and transported away by pincher 37. However, because chamber 13 must be reconfigured to accommodate and utilize rotor 51, the rotor is ejected from magnet chamber 13 by a blast of compressed air. As can be seen in FIG. 2, piston 21, inner piston 42 and collar 43 are each hollow in the general vicinity of fingers 41. Even if pincher 37 is appropriately positioned above assembly 15 with fingers 41 opened when such ejection occurs, it is difficult, if not impossible, to have fingers 41 close on rotor 51 in time. Rotor 51 can then be carried by the ejecting blast of air up into piston 21, which can cause damage to and/or loss of the sample. Furthermore, if pincher 37 is maneuvered by the rest of apparatus 17 while fingers 41 are fully extended, then those fingers can catch on and damage other portions of the apparatus of FIG. 1, and/or damage other apparatus, during movement of pincher 37.